-LRB- CNN -RRB- -- Just when cruise lines thought they might be headed for calmer waters ...

At least 162 passengers and 11 crew members have reported being ill on board Princess Cruises ' Caribbean Princess , according to the Centers for Disease Control and Prevention .

The institute said health officers would board the ship in Houston to investigate the gastrointestinal illness , which is causing vomiting and diarrhea .

The news follows reports of sickness this week on another cruise ship , this one from the Royal Caribbean line .

Nearly 700 crew and passengers fell ill aboard the Royal Caribbean 's Explorer of the Seas , the highest number of sick people reported on any cruise ship in two decades , CDC data show .

That ship returned home Wednesday , two days earlier than expected .

To compare the cruises , 5.22 % of passengers on the Caribbean Princess reported being ill , versus 20.5 % on the Explorer of the Seas .

The outbreak on board the Caribbean Princess has been confirmed as norovirus , according to Julie Benson , a spokeswoman for Princess Cruises .

Are cruise ships floating petri dishes ?

Noroviruses spread easily and are a common cause of gastroenteritis , which produces vomiting and diarrhea .

Norovirus is also suspected on board the Explorer of the Seas , though the cause of the illness there has not been confirmed .

Caribbean Princess is expected in Houston early Friday . The seven-day cruise is being cut short by one day .

Sick passengers are being asked to stay in their cabins , while staff disinfect public areas such as restrooms and elevators .

The decision to cut the trip short was made based on forecasts for heavy fog , not the outbreak , Benson said .

CNN first learned of the stricken Princess ship from a Twitter post by the Houston Chronicle .

Royal Caribbean cruise ship returns home - with a sickness record

CNN 's Miriam Falco contributed to this report .

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More than 5 % of passengers on the Caribbean Princess report being ill

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A spokeswoman says the outbreak has been confirmed as norovirus

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Passengers and crew experience vomiting and diarrhea